Replace #flat_map with #map.flatten
Add tests for callbacks with out parameters in GIMarshallingTests
Add skipped tests for new items in Regress and GIMarshallingTests
Add passing tests for Regress::LikeXklConfigItem
Add passing tests for fields in Regress::TestSimpleBoxedA
Fix handling of containers containing objects
Add passing test for GIMarshallingTests.gvalue_in_with_modification
Restore compatibility with Ruby 1.8.7
Start handling aliases of container types